Part I: A computer program for the simulation of telecommunication systems: application to optical transmission systems

The conception and analysis of optical transmission systems employing various optical devices (semiconductor lasers, optical fibre, optical amplifiers, photo-diodes,…) require the support supplied by simulation software dedicated to the new components. The objective of thecnet/ipsis collaboration is to respond to this need. In this first article we present the simulation tools which characterize the quality of a digital transmission system, as well as the modelling of the optical elements. In order to show its full range of capabilities in the optical domain, a second article describes the results obtained from the simulation of digital transmission system using wavelength multiplexing.     

Informed consent: The effects of clarity and specificity on disclosure in a clinical interview.

Replicated and extended the findings of T. Muehleman et al (1985) that informing clients of the limits of confidentiality is not necessarily detrimental to disclosure. 32 single mothers (approximate mean age 34 yrs) were assigned to 1 of 3 groups receiving an informed consent form prior to a clinical interview. The forms differed in the amount of specificity and clarity of information pertaining to the limits to confidentiality. Results indicate that when the limits to confidentiality were conveyed in a clear and specific manner, there was no decrease in disclosure. Contrary to these findings, 27 clinical psychologists who were surveyed predicted that increasing clarity and specificity of information concerning the limits to confidentiality would lead to decreased disclosure by the interviewees. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Design of adaptive feedforward algorithms using internal model equivalence

The paper investigates the design of adaptive feedforward cancellation (AFC) algorithms with sinusoidal regressors for repetitive control. Such adaptive algorithms are equivalent to linear controllers based on the internal model principle (IMP). Using this equivalence and root locus rules, the phase advance of the regressor of the adaptive algorithm can be chosen to maximize the phase margin at low gains. A surprising result is that selecting the optimal phase advance is equivalent to placing a zero in the open right half-plane in certain cases. A complete design and analysis for the compensation of a single-frequency periodic disturbance is done. A new variation of the AFC algorithm is also developed in which the adaptive portion acts in parallel with a feedthrough term. the IMP equivalent of this algorithm has two zeros instead of one. Analysis and simulation show this method to have superior convergence and robustness properties when compared with the method having no feedthrough term. Discrete time versions of the algorithms are briefly considered.     

Hierarchical approach to modelling of liquid-crystalline polymers

Summary Liquid-crystalline polymers exhibit fascinating structure at many size scales. This paper describes how computer models at different size scales can be linked together by a hierarchical approach to give a better understanding of the properties and behaviour of these materials. The atomic scale is considered first, where semi-empirical molecular orbital techniques are used to calculate the torsional energy functions associated with rotating the backbone bonds of the polymer. Secondly, entire chains are simulated using a Monte Carlo technique based on the torsional energy functions to deduce the persistence length of the polymer of interest. A theoretical relationship enables the Frank elastic constants to be determined from the persistence length. The elastic constants may then be used as input parameters for models both to predict microstructure and to help understand the role of defects in the shear flow of these materials. The hierarchical approach provides a meaningful framework within which data obtained from small-scale models are used to parameterise models at a larger scale.     

Beyond the Crisis Window for Reform: Some Ramifications for Implementation

In the policy literature, crises are often presented as opportunities for reform initiation. Little is known, however, about the effects that crises may have on the implementation of such reform initiatives. This article explores how a crisis may affect the administrative relations between central authorities and field administrations. The crisis impact on central-field relations appears to be twofold. First, a crisis may facilitate, if not induce, the centralization of decision-making processes. Secondly, a crisis may affect the degree of consensus between central authorities and field administrations with regard to problem definitions and preferred solutions. This paper uses a case study of the Dutch prison system to explore the crisis impact on these two dimensions of central-field relations. In this particular case, crisis circumstances did not facilitate a successful implementation of a major policy overhaul. We suggest that crises may offer opportunities for reform implementation, but only under highly restricted conditions. When these conditions are not met, crises may have perverse effects on central-field relations which limit the prospects for the effective implementation of reform.     

Mesure automatique des paramétres de bruit des MESFET hyperfréquences

An automatic noise parameter measurement test set is described in two sections : (i) A novel noise parameter extraction procedure from a set of noise figure measurements is developped. The experimental minimum noise figure is no longer required and the sensitivity to measurement incertainties is found to be very low. (ii) An automatic input tuner with a large number of precalibrated and reproducible positions is designed and realized. The last part give examples of broadband (8 to 17 GHz) noise parameters characterization ofmmic GaAsmesfets when both the automatic tuner and the extraction procedure are used.     

Data-driven and tool-supported elicitation of quality requirements in agile companies

Software Quality Journal - Quality requirements (QRs) are a key artifact needed to ensure the quality and success of a software system. Despite their importance, QRs rarely get the same degree of...     

Software engineering practices and Simulink: bridging the gap

International Journal on Software Tools for Technology Transfer - Although widely used in embedded systems design, Matlab/Simulink is not considered a state-of-the-art design environment by the...